Circular slide-rule.



Patented. Feb. 20, 1912.

erzw @am HERBERT, RICHARD WATTS, or BRooELANDs, ENGLAND.

CIRCULAR SLIDE-RULE.

Specification of Letters Patent. Application filed January 23, 1911.

Patented Feb.

20.1912: Serial No. 604,037`

To all whom it man; concern:

Be. it known thatl I, HERBERT RICHARD llVArrs, a subject of the King of England, residing at Brooklands, in the county of Chester, England, have invented new and useful. Improvements in Circular Slide- Rules, of which the following is a specification.

The object ot this invention is to provide a circular slide rule in which the parts'are reliably connectedv so that they will not become displaced or loose during ordinary use, also to prevent warping or distortion of the parts and interference with the 'tree use ot theinstrun'ient, and also to simplify the construction so as to permit ot making the same at reduced cost.

In the accompanying drawings: Figures 1 and 2 are front and rear face views of my improved circular slide rule. Fig. 3 is a cross section of the same, on an enlarged scale.

Similar letters ot reference indicate corresponding parts throughout fthe several views.

My improved circular slide rule comprises two dial disks a., a1 arranged within two dial rings Z), L1 each disk and ring together forming a dial.` The two dials are surrounded by a metal'rim or frame c and protected on both sides by transparent panes or disks (l, (Z1 which are seated at their edges-in rabbets D, Dltormed on opposite sides of the rim and which may be constructed of glass, Celluloid orother suitable material. Each pane bearsacursor or hair-line f marked radially thereon and is capable of being revolved by the two thumbs ofthe hands of the operator in orde-r to set the cursor or hair-line to the required position. TheV center disks a, al of the dials are revolved by pressing the sections e, el of a thumb piece on opposite sides between the finger and the thumb off the hand and then turning these parts relatively to each other to the required position.

A spacing disk or washer (f/ ot' brass or other metal is interposed between the central parts a, al of the dials and a spacing ring /t is interposed between the outer parts 1 ot the dials. The inner edges oi the dialrings o. 1 stop short of the corresponding edge of thespacing ring /lzI and the outer edges of the dial disks project "beyond the outer edge of the spacing disk\and bear against opposite sides of the inn r edge of the spacing ring, thereby holding the movable parts of thedial in place relatively to each other. The outer dial sections t), 211 are secured to opposite sides of the spacing ring by any suitable means but preferably by one or 'more' screws /lz1 and cement and the three parts 7J, (J1, 7L, thus united are helagainst turning in the rim by a screw v' ot' a hanger passingradially through a threaded opening in the'rim and provided at its inner end with a dowel pin or spur j which enters an opening in the spacing ring and provided at its outer end with a handle or loop .7.l for suspending the instrument.

The two sections e, el ot the thumb piece have hubs E, El on their 'inner sides which project through central openingsIH, H1 in the glass disks and bear against the outer sides of the central dial sections Z), 711-. The latter are connected lwith the spacing'washer g and thumb pieces e, el] so that these parts turn together. by a central connecting screw Z and two side connecting screws m, m ar-A ranged on opposite sides ot" the central screw. It desired the central screw may be omitted. 'One of the thumb pieces has a hollow dowelnl at its inner end whiclrenters openings in the 'centers of the dial 'sections a, al and washer g for centering the same. This means of fastening Atogether the thumb piece sections, the dial centers and the washer lis superior to the means heretofore employed for this purpose and is also less expensive to make.

By constructing the washer and spacing ring of met-al the same are not liable to warp or distortand make the ilrs-trument' work hard and wear unduly.

The 'ront face of the circular slide rule shown in Fig. l, is thatfwhich contains tive circles of"scales which are arranged and used as followwgThe outer one a: on the front-'ring b1 is a scale of logarithms. The front cursoror 'hair-line f is moved over any number on the inner scale A on the front ring b1 and the log is read on scale Scale A on the ring 1 and scale B on the front disk al are calculating scales for multiplication, division and proportion. Square roots are extracted by associating the scale B with scales x1 and m2 on the front disk a1 move the arrow on the front` To multiply, disk under any number on scale A and over any number on scale B and read the answer on scale A. To divide any number on scale A,lput the divisor on scale B under the' divilos.

dendon scale-A and the arrow on scale B will point to the quotient on scale A. For proportion, put any number on scale B un-V der any -number' on scale A and the proportion of those numbers will be the y'saine varound'the whole of the scales A and B.

The circular scales m1 and C arranged on the front dial disk bear the square roots of numbers on scale B. The cursor or hair .line is moved over any number on scale B Vand the square-root is read on scales :v1

and C.

Vscale A- of the rear ring b.

-The rear face of the circular slide rule vcontains six circles of scales which are arranged and used as follows :-The outer scalevy onthe ring Zi is a scale of angles, it represents the degrees. To find they sine of vany angle,`move the cursor or hair-line of Lof workin .eighteen days,'how many Vmen will it take to do it in six days? Operation:

Setten' on` rear scale B to eighteen on rear scale A 'and under six on rear scale` A read the'answer thirty on rear scale B. The' rear scales A: and B thave the same divisions,l

.- but lthey are reversed to `one another.

Scalesz, 21 and z2 on the rear disk a form a; contimious scale and bear the cube roots of numbers on rear scalesA and B. The rear hair-line is moved over any number on rear scale B1' and the cuberoots are read onl the -rea-r scales, 21 or z2. l

v I claim as my invention.:

1. yA circular slide rule comprising' a spacing, ring, dial rings secured to opposite sides of the spacing ring and having their inner edges'stopping short of the corresponding edge of the spacing ring, a spacing disk arranged within the spacing'ring, and dial disks secured to opposite sides of the spacing disk and arranged within the dial rings and having their outer edges projecting beyond the corresponding edge of the spacing disk and engaging with opposite sides o the spacing ring.

2. A circular slide rule comprising a spacing ring, dial rings secured to oppo;

site sides of the spacing ring and having their inner edges stopping short of the cor- 3. A circular slide rule comprising a spacing ring, dial rings secured to opposite sides of Ithe spacing r1ng` and having thelr inner edges stopping short of the` corre- .sponding edge of the spacing ring, a spacing disk arranged within the spacing ring, dial disks secured to opposite sides ofthe spacing disk and arranged within the dial rings and having their outer edges projecting beyond the corresponding edge of the spacing disk and engaging with opposite sides of the spacing ring, a rim inclos ing said spacing and dial rings, and a hanger having aA screw passing through a threaded opening in the rim and provided with a dowel entering the edge of the spac -ing ring.

4. A circular slide rule comprising a spacing ring, dial rings secured to opposite sides of the Vspacing ring and having their inner edges stopping short of the corresponding edge of the spacing ring, a

vspacing disk arranged within the spacing ring, dial disks secured to opposite sides of the spacing disk and arranged within the dial rings and having their outer edgesproject-ing beyond the corresponding edge of ,the spacing disk and engaging with opposite sides of the spacing ring, said spacing and dialdisks being provided with central openings, and thumb pieces secured cen trally to opposite sides of the dial disks and one of said thumb pieces being provided with a dowel which enters the openings oi said spacing and dial disks.

Witness my hand this sixth day of January, 1911.

HERBERT RICHARD WATTS.

Vitnesses:

JOHN Jnssor, FREDK. WVM. Bnooiis.V 

